1. Field of the Invention
This invention relates to a display apparatus, especially to a driving circuit applied to a LCD apparatus.
2. Description of the Prior Art
In general, a liquid crystal display system includes a pixel matrix, two polarizers and a plurality of driver chips. These driver chips are usually packaged by chip on film (COF) technology and coupled to a panel peripheral circuit, so that each row and each column of pixels of the panel can be driven by a driving voltage signal. As shown in FIG. 1, a plurality of gate driver chips IC1˜ICN are coupled in series by the wires disposed on the array substrate WOA, wherein N is a positive integer larger than or equal to 2.
However, with the increasing size and better display quality of the LCD panel, the number of gate driver chips needed in the LCD panel must become larger and the length of WOA wire needed in the LCD panel must become longer.
As shown in FIG. 2, the driving circuit 2 including a first driver chip IC1 and a second driver chip IC2 is taken as an example, if L output channels corresponding to the first driver chip IC1 are CH11˜CH1L and L output channels corresponding to the second driver chip IC2 are CH21˜CH2L; R1 is the internal resistance of the first driver chip IC1 which is the total of the resistances of the L output channels CH11˜CH1L; R3 is the internal resistance of the second driver chip IC2 which is the total of the resistances of the L output channels CH21˜CH2L; R2 is the resistance of the WOA wire coupled between the first driver chip IC1 and the second driver chip IC2. Wherein, L is a positive integer.
It should be noticed that the internal resistance R1 of the first driver chip IC1 will be uniformly distributed among the L output channels CH11˜CH1L of the first driver chip IC1 and the internal resistance R2 of the second driver chip IC2 will be uniformly distributed among the L output channels CH21˜CH2L of the second driver chip IC2. Thus, the equivalent resistance from the signal source SS to the last output channel (the L-th output channel) CH1L of the first driver chip IC1 is R1 and the equivalent resistance from the signal source SS to the first output channel CH21 of the second driver chip IC2 is (R1+R2). Compared to the internal resistances R1˜R2 of the first driver chip IC1 and the second driver chip IC2, the WOA wire has higher resistance and this will cause obvious difference between the output signal intensities of the last output channel (the L-th output channel) CH1L of the first driver chip IC1 and the first output channel CH21 of the second driver chip IC2, and the display quality of the LCD panel will also become poor, even a brighter region will be generated in the center of the dark band of the display frame, such as H-band or H-block phenomenon which should be solved.